Field questions are an important fact-gathering tool. Here are some more commonly asked questions from the field. The answers are provided by Kele Sales Engineers - people who can make a big difference in your project and product performance.

A: It is not unusual for definite purpose contactors, motor starter coils and even some relays that are powered by AC voltage and are electrically held to make a minor electrical humming sound. The intensity of the hum will vary with the size and type of device and is often amplified when the device is mounted in a metal enclosure. It is best to locate these devices in an area like a mechanical room where noise is not an issue. If they must be located in a noise sensitive area such as above a ceiling, a piece of foam (polyethylene closed cell pipe insulation works well) located between the contactor and its mounting surface will minimize hum and vibrations.